function [y] = speed_calc(t, y, acceleration_calc)
t = 1 %Initial value for t
y = 1 %Initial value for y
h = 0.1 %Stepsize

%Get first derivative
f1 = acceleration_calc(t, y);
f2 = acceleration_calc(t + h/2, y + h*f1/2);
f3 = acceleration_calc(t + h/2, y + h*f2/2);
f4 = acceleration_calc(t + h, y+h*f3);
y = h*(f1 + 2*f2 + 2*f3 + f4)/6;